Develop algorithms for calculating the heat transfer and temperature in simple and small biogas digesters buried into the soil
Tutor / Supervisor
G. Sommer, Sven
Martí Herrero, Jaime
Student
Teradas ILL, Georgina
Document type
Master thesis (pre-Bologna period)
Date
2012
rights
Restricted access - author's decision
Publisher
Universitat Politècnica de Catalunya
UPCommons
Abstract
Biogas digesters are used to produce methane from anaerobic digestion of animal
manure in long lot of developing countries to replace wood as the traditional source of
fuel to produce energy for domestic purposes. A variety of factors affect the rate of
digestion and biogas production. One of the most important is temperature. Simple and
small fixed dome digesters are partially or totally buried into the soil are widely used
with more than 30 million having been constructed in Asia. For this reason, this study is
focused on these. Temperature inside the digester is affected by many heat transfer
phenomena which depend on of many parameters from the environmental conditions
where the digester is installed: like ambient air temperature and soil temperature
profiles. The algorithm developed takes into account these situations for simple and
small digesters and in which input data required are easily available. To improve other
studies of heat transfer models and temperature of heated lagoon digesters or floating
drum digesters the algorithm includes some variations: the effect of the temperature of
the slurry feeding, gas volume variations and soil temperature dependence on depth.
The model elaborated is an acceptable first approximation of the model desired, as the
model has been tested using data from Hanoi, Vietnam, cause the monthly average
errors of computed temperatures are below 20%. To better understand how heat transfer
phenomena are acting or which is the most influent or how much heat transfer is
exchanged, more studies should be carried out using the model develop here because
any remarkable conclusion cannot be deduced from obtained results.
Participating teacher
- G. Sommer, Sven
- Martí Herrero, Jaime